Inorganic and Nanomaterials

Question 1

Long Range Order

Answer 1

crystalline

continuum of order

Question 2

Short Range Order

Answer 2

amorphous

continuum of order

Question 3

ReO3

Answer 3

vertex sharing octahedral

Question 4

TiO2

Answer 4

rutile
anatase
brockite

Question 5

Carbon Allotropes

Answer 5

graphite
diamond
fullerene

Question 6

Defects

Answer 6

0 K perfect crystallinity
thermodynamics drive defect formation
requires input of energy
increased entropy

Question 7

Intrinsic Defects

Answer 7

Schottky - vacancies present
Frenkel- displacement of an ion moving between
n(s/f) = Nexp(-deltaH(s/f) / 2kT)

Question 8

Extrinsic Defects

Answer 8

introducing ions
doping
electron donating atom e.g. K+
electron can be a suited into conduction band

Question 9

Non-Stoichiometry

Answer 9

defects and doping
TiO same as NaCl Rock salt
TiOx 0.7 1 titanium vacancies

Question 10

Solid Solution Non-Stoichiometry

Answer 10

substitutional - new atom replaces existing

interstitial - atom added

Question 11

Long Range Ion Movement

Li Ion Batteries

Answer 11

C6 + LiMn2O4 —> LixC6 + Li1-xMn2O4
2 x electrodes 1 x electrolyte
layers, channels, pores provide holes for Li+
intercalation xLi + C6 –> LixC6
deintercalation LiCoO2 –> xLi+ + e- + LixCoO2
0

Question 12

Ecell

Answer 12

Ecell = Eanode - Ecathode
W = V x A
Ah = A x h 
E = W x h

Question 13

Localised Ion Movement

Answer 13

radio, radar, sonar, ultrasound
ion in asymmetric site
local dipole movement

Question 14

Ferroelectrics

Answer 14

apply electric field to displace an ion
high dielectric strength: not break down at high voltage
low dielectric loss: not lose electrical energy as heat
stored charge can be measured in parallel plate
Q = CV
Er = Cdielectric/Cvacuum

Question 15

BaTiO3 Perovskite

Answer 15

> 120C Ti in symmetrical Oh
thermal motion generates sufficient chemical pressure to stabilise cubic structure
5-120C Ti displaced resulting in polarisation
motion reduced, structure distorts

Question 16

Piezoelectrics

Answer 16

polarise under action of mechanical stress - pressure
tetrahedral groups
alternating electri. field causes vibrations

Question 17

Pyroelectrics

Answer 17

polarisation which is temperature dependent
thermal expansion/contraction of lattice
changes the size of the dipoles

Question 18

Paramagnetism

Answer 18

unpaired electrons
magnetic dipoles do not interact
temperature decreases, dipoles align parallel with the field

Question 19

Antiferromagnetism

Answer 19

no applied field needed to align dipoles
spins anti-parallel
Tn Neel: antiferromagnetic-paramagnetic transition

Question 20

Ferromagnetism

Answer 20

cooperative magnetism where applied field not needed to align spins
spins parallel
Tc Curie: ferromagnetic-paramagnetic transition

Question 21

Ferrimagnetism

Answer 21

cooperative magnetism where applied field not needed to align spins
spins anti-parallel with partial cancellation

Question 22

Superexchange

Answer 22

interaction of metal ions mediated by anions

overlap atomic orbitals

Question 23

Leading to Antiferromagnetism

Answer 23

metal monoxides
Rock salt structure
Oh sites
2 x eg each containing unpaired electrons

Question 24

Leading to Ferrimagnetism

Answer 24

2 sublattices, 1 with greater magnetic moment than the other 
electrically insulating 
2 metal sites 
spinel: [A2+]tet[B3+]oct
inverse spinel: [B3+]tet[A2+,B3+]oct
M3+ prefers octahedral 
small cation prefers tetrahedral

Question 25

Domains

Answer 25

not all Fe magnetic at room temperature apply a magnet next to it - magnetises below Tc temperature antiparallel--flux generated-- magnetic

Question 26

Demagnetised

Answer 26

cohesive field

Question 27

Superconductivity

Answer 27

zero electrical resistance Meissner: external. angelic field ejected large magnetic field generated support large currents without resistive heating

Question 28

Cup rates

Answer 28

high Tc CuO2 planar layers separated by charge reservoir layers control Cu oxidation states

Question 29

Borises

Answer 29

MgB2 B in interstites of Mg hexagonal layers

Question 30

Fullerides

Answer 30

intercalation of metals into C60 lattice electron transfer to C60 electrons move through layers

Question 31

Cooper Pair

Answer 31

mutual attraction of electrons attraction of electron to lattice ion lattice distorts slightly second electron attracted by ion displacement electron-phonon coupling

Question 32

Wet Chemical Method

Answer 32

prepare soluble nanoparticles prevent aggregation causing precipitation coat surface bulky ligands, fatty acids, amines, thiols size and shape can be controlled

Question 33

X-Ray Diffraction

Answer 33

single crystal m des width of peak increases with size t = ky/ Bcos@

Question 34

Semiconductor

Answer 34

conduction band photon absorbed exciton generated relaxation leads to luminescence